1. Field of the Invention
The present invention relates to a tire pressure monitor and more particularly, to a tire pressure detector installed inside a tire, which provides an insulation sleeve to isolate the electrical transmission between an external air faucet and the tire pressure detector so that the external air faucet becomes an independent transmitting antenna being unaffected by the shield from the steel wire tire.
2. Description of the Related Art
After some time of driving, exposure to the sunlight or the fall of temperature at night, the tire may lead to some extent and the tire pressure will fall down under a normal pressure of 28 psi. It brings a potential danger for the driving safety. Particularly, if one tire of a high speeding vehicle due to the insufficient tire pressure breaks up, the result is very destructive.
Therefore, plenty of researchers have been devoting to developing this kind of detecting and monitoring devices that monitor the tire pressure during driving. Such disclosures include TW 536489, TW 400811, TW 149143, TW 177543, TW 560445, TW 574977, TW 090946, TW 100539, TW 396974, etc. The working principles of above mentioned patents can be divided into electronic detecting and mechanical detecting groups. The life span of the mechanical one is relatively shorter, and the device body is bigger and the detecting precision is not good at the same time. Such kind of mechanical detecting devices is not the object of the invention so that no further descriptions thereto are given hereinafter.
The most popular design of electronic tire pressure detecting apparatus is installed in the steel wheel rim for the tire. Such kind of apparatus has been disclosed in TW 404354, TW 578706, TW 578707, etc. The advantage of the design is that the tire pressure can be measured directly by the tire pressure monitoring apparatus inside of the tire. The main structure is shown in FIGS. 1 and 2. It consists of a body 11 and a detecting circuit board 12 which is set in the body 11. This circuit board 12 has a signal transmission antenna 13 and two batteries 14 which supply power to this circuit board 12. In the front of the body, an air inlet 15 is mounted. When the above described components are assembled into a tire pressure monitoring apparatus 10 (shown in the FIG. 2), the whole set will be fixed on a steel wheel rim 21 inside of the tire 20. The air inlet 15 penetrates this steel wheel rim 21 and it is fastened by a plate 16 and a screw 17. At last a protecting head 18 will be screwed up and the assembly is finished.
The above mentioned conventional tire pressure monitoring apparatus 10 will transmit a signal through the signal transmission antenna 13, when it detects an abnormal tire pressure. The warning signal will be received by a receiver (not shown in the drawings) in the vehicle and the driver acquires a message about the abnormal tire pressure. However, the signal transmission antenna 13 is mounted in the tire 20 structured with a plurality of layers and with a steel wire annulus 22. Thus, the wireless signal, when being transmitted, is covered by the steel wire annulus 22 inside the tire, due to an electromagnetic eave, or the transition of wireless signal is interfered by the wheel rim 21, thereby accuracy and reliability being poor, which is the defect of this mentioned tire pressure monitoring apparatus.
Although some researchers try to extend the signal transmission antenna 13 to the air inlet 15 outside of the wheel rim 21, the signal still could not be sent out of the tire 20. It is the problem of prior designs which cannot effectively transmit the signal. Therefore, it is desirable to provide a tire pressure monitor, which achieves effective transmission effect.